Propilenglicol

Propilenglicol, also known as propylene glycol, is a clear, viscous liquid with the chemical formula C3H8O2 and the systematic name 1,2-propanediol. It is miscible with water and many organic solvents, has a boiling point of 188.2 °C and a freezing point around −59 °C, and is hygroscopic. It has a mildly sweet taste and is widely used as a solvent and humectant.

Industrial production uses the catalytic hydration of propylene oxide to give propylene glycol; purification yields USP-grade material for pharmaceutical and food uses.

Applications include use as a humectant, solvent, and plasticizer in foods, cosmetics, and medicines. In the food industry it is listed as E1520 in the EU and several other regulatory jurisdictions. It is also used as a heat-transfer fluid and antifreeze, and as a solvent in pharmaceutical formulations and in e-cigarette liquids as a base.

Safety and regulation: Propylene glycol has relatively low acute toxicity and is approved for many consumer uses. It is generally recognized as safe for food use in permitted amounts. However, at high exposure it can irritate the skin and eyes, and ingestion in large amounts may cause gastrointestinal symptoms and central nervous system effects.

Environmental and biodegradation: Propylene glycol is readily biodegradable and has low acute toxicity to aquatic life. It is miscible with water, so spills should be contained to minimize exposure to waterways, and recovery or appropriate treatment is typically employed in industrial settings.